Pneumatic hammer



Aug. 7, 1.928.

G, SMITH PuEUuTIc HAMMER y Fledrch 19, 1925 3 Sheets-Sheet 2 .fa l J .5 Tr

-" --.nm t) @msm Aug. 7, 1928.

G. W. SMITH PNEUMATIG HAMHER Filed March 19., 1925 5 Sheets-Smet 5 K a' lvsmon wn'NEssEs ATTO RN EY Patented Aug. 7, 192s.

, UNITED STATES 'PA'rENr OFFICE.

GEORGE WALTER. SMITH, OFOTTUMWA, IOWA, AssiGNOR To. yminnsooor WONDER DRILL COMPANY, OF OT'rUMWA, IOWA, A cORroRA'rrONOF IOWA.v

PNEUMATIC HAMMER.

Application rfiled March 19, 1925. Y Serial No. 16,690. Y. l

This invention relates to pneumatic hammers adapted to be operatedbycompressed air of the type known as semivalveless, wherein the passageof the air iscontrolled by the kmovement of a piston and a single valve cooperating therewith. i

The general ob `ect` of lthe invention is to] provide a tool of this type in; whichfthe valve is actuated more quickly and positively than is the case with tools as heretofore -constructed, this being vaccomplished by bring-l ing the live `orunexpanded air into direct contact with the valve to open andclose the same, thus obtaining better results with' a smaller consumption of compressed air.

The invention consists further in certain details of construction and combinations of elements, the advantages of which will be more particularly explained in connection withthe accompanying drawings illustrating the invention in its preferred form. 'Y

In the drawings: Figure' 1 is a longitudinal section showing the plunger in its rearward or retracted position.

Figure 2 is a similar viewfshowing the plunger inits :forward position. Y

Figure 3 is an enlarged longitudinal section through the rear portion ofthe tool, the section being taken substantially as indicated by the line 3 3 on Figure 2.

Figure 4 is a transverse section taken on the line 4 4` of Figure 1.

Figure 5 is a transverse section taken on the line 5 5 of Figure 1.

Figure 6 is a transverse section taken on the line 6 6 of Figure 2.

Figure 7 is a section through the valve cage takensubstantially on the line 7 7 of Figure 6. y l f VFigure 8 is a transverse section taken on lthe linev8 8 of Figurel.

Figure 9 is a transverse section taken on the line 9 9 of Figure 3.

vReferring in detail to the .-drawings, the tool comprises a cylinder having a main body. portion 1, a -rearward portion A2v containing the valve and constant pressure chamber, and a rear .head 3. For convenience in machining, the sections 1, 2 and 3 are made separately and afterward secured in assembled relation by means of bolts 4, shown in Figure 3, which extend through holes 5, 6 and 7 in the respective sections 1,

2 and 3, grooves 8 being formed longitudinally of the section'1 to provideA a clearance for the'bolt heads when assembling.' The lower or forward end of the main bodyportion 1 is also provided withholes 9 in alinement with the grooves 8 forreceiving bolts,A which secure the lowervhead 10 and the drill holder 11.

The loweror front lportion ofthe section i yconnected by a neck 1.6 which .isof smaller diameter than 'either the shank or head.

The sectionf2 has a central bore4 17 forming a continuation of the ycylinder portion 14, and communicating'vat its rearor upper end withr a'constant pressurechamber 18 to which compressed air isr'supplied through aV passageway 19, having kat vits inlet'end .a socket L2O adapted to `vbe Lconnected to vthe vcom-pressed air supply. VThe; passage of the lcompressed air through thepassageway 19 is controlledby means ofj a valve 21, which is normally urged to closed position ybyav spring 22, and may be opened by means ot ar lever`23located in the handle 24, which is securedfto the head 3.V The constant pressure chamber 18 Vcommunicates through a port or passageway. 25 with the lower part of the cylinder portion 14.

The larger cylinder portion 1-2 is provided with one o1' more exhaustportsor passagethe lower' end of theA larger cylinder portion 12 atV the proper time by means of a passageway or port 27 leading from the constant pressurechamber18,and a passageway 28Hopening into thelower end of the cylinder. Thepassage-of the i air through '100V the `port 27 and passageway 2S is controlled by means of avalve 29 mountedl for reciprocation in a valve cage 30, and having an enlargedrlhead 31. The valve 1sv openedat the proper time by livevv air .introduced underneath .the head 31by llneans of a duc-t ways 26, and compressed air is supplied to v 32 Ileading 'from the lower part of the smaller cylindrical portion 14, and is closed at the proper .timeby means of live air introduced into the chamber 30, above the head .31, through a duct 33 leading'from the upper part of the larger cylindrical portion 12. In the operation of the tool, when the parts are inthe position shownin Figure 1,

l and'live air enters the valve cage underneath the head 31, and immediately opens the valve. The compressed air, which previously .acted onl the upper face of the valve 20, has

at this time been vented through the duct 33, the large cylinder portion .l2 and the ports 26'. vThe compressed air now enters through the port 27 and passageway 28 into the lower end of the larger cylinderportion 12 under iieath the piston head 13 and raises the same, since the pressure on the end of the head 13 is much greater than the pressure on the com paratively small end of the shank 15.. Meanwhile the compressed air within the upper part of the larger cylinder portion 12 has been vented through the ports 26.` As the piston head 13 rises and closes the ports 26,

. the small amount vof vair at atmospheric presw sure, which is trapped inthe upper part of the larger cylinder'portion 12,.,is compressed into pockets 34 eXtending upwardly from the upper end of said larger 'cylinder portion'andy terminating near the' upperpart of the section 2, as indicated by dotted lines in Figure 3. This permits the piston; upon its rearward stroke, to yreach the eXtreme endof the larger cylinder portion 12,'and at the saine time cushions the'rearward stroke of the piston. As the piston shank 15, upon its rearward stroke, uncovers the poi-t 25, live air. is admitted to the upper part ofthe larger cylinder portion 12 and through the duct v33 yto the chamber 80 above' the valve head 31 vand closes the valve. During .the rearward movement of the piston head 13,' it uncovers the exhaust ports 26 to release the compressed air from the4 lower end of the larger cylinder portion 12. 'At the time that the port 26 is uncovered, however, the piston has acquired sufficient momentum to carry 'it to the inner end of its stroke.

At the time when live air is introduced through the duct 33 to the chamber v`30 to close the valve, the inner end of Vthe duct 32 '35 extending from the duct/32 through the wall of the section .2, as shown in Figure 7 Tliisbleed hole 35, however, is lquite small compared with the size of the duct 32, Figures 6 and 7, so that it does not interfere with the immediate and positive .opening of the `valve by the incoming .livefaiig at the conclusion of the forward stroke.'

lt will be noted that each of the exhaust ports 26 is comparatively large so .that the used air, at the end of eachl stroke, may be immediately vented. There is also a small port 37 near the bottom of the cylinder,

'which connects withoiie of the exhaust ports stantially-the entire downward stro re, thus overcoming any tendency for the valve to open prematurely under the influence of any back pressure which may be exertedv through the passageway 28.V The several ports and ducts'are so arranged that nothing but'live air actuates the valve, thereby resulting in a positive and quickly responsive valve action. This results in a quick and positive action of the plunger or hammer, andjcuts down very materially the consumptionV of compressed air, and the consequent lexpense of operation. e p

While I have shown and; Vdescribed specifically the construction of the invention in i its preferred formit isapparent that numerous modifications may beinade in the construction andlarrangeinent of the various parts without anymaterial departure from the salient features 'of the invention. It is my purpose, therefore, to include all`s'uch modifications Within the scope of the appended claims. l

What is claimed is: y 1. In a pneumatic hammer, a cylinder large diameter and 'a rearward 'portionof comparatively small diameter, a pistonliaving 'a head sliding in the larger forward having a forward portion of'comparatively .l

portion of the cylinder, a shank sliding in the smaller rearward portion of thecylin-v der, and a neck connecting said headjand shank and having a diameter less thanI either,

means forconstantly admitting fluid under pressure to the rea-r.' end of the rearward portion of the cylinder, ineansfor vintermittently admitting said fluid to the rearward end of the larger forward portion of the cylinder, a passageileading from y'the constantpressure end of the cylinder` to the opposite end and opening into the larger forward portion ofthe cylinder, a valve for controlling said passage, a valve 'chest for said valve, av port leading from the smaller portion of the cylinder to one end of the valve chest but independent of said passage and uncovered by the shank ol the 'piston toward the end ot' its forward strokel to admit fluid under pressure to open said L valve, another port'leading from the larger forward portion oit the cylinder to the other end of the valve chest and serving to admit fluid to close said valve toward the conclu- Sion of the rearward stroke, a bleed holer comparatively small diameter, a. piston having a head sliding in the larger port-ion of the cylinder and a. shank sliding in the smaller portion thereof, means for intermittently admitting compressed air to the rearward end of the larger portionot Said cylinder, a. passage for admitting compressed air to the forward end of said larger portion of the cylinder, a Valve for controlling said passage, a rvalve chest for said valve, a port leading from the smaller portion of the cylinder to one end of the valve chest but independent of said passage and uncovered by the shank ot the piston toward the end of its forward stroke to admit live air to open said valve, another port leading from the larger forward portion of the cylinder to the other end of the valve and -uncovered bythe head ot' the piston during its rearward stroke to admit live air to close said valve, an exhaust port leading from the larger portion of the cylinder and also controlled by the yhead of the piston, and bleed holes leading from t-he respective ends of the valve chest and each serving to exhaust the air fromr one end of the chest while the valve is being actuated by live air admitted to the other end. y

In testimony, that I claim the foregoing as my own, I have hereto atlixed my signature.

` GEO.y WALTER sMrrH.

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